The present invention relates to spiropyran compounds. In particular, the invention provides indolinospiropyran compounds and methods for their manufacture, which compounds are useful as photochromic compounds.
Various classes of photochromic compounds have been synthesized and suggested for use in applications in which reversible color changes or darkening is induced by sunlight. For example, spiro(indolino)naphthopyrans and spiro(indolino)quinopyrans are described in GB Patent 2,174,711. Spiropyrans also are described in Brown, Glenn H. ed., Photochromism (New York, 1971) and Durr, Heinz and Henri Bouas-Laurent eds., Photochromism (Elsevier, 1990).
Spiropyran derivatives may be the best known organic compounds showing photochromism phenomenon, but the structures of reported spiropyrans are considerably limited. Thus, a need exists both for spiropyran compounds allowing further facile modifications as well as methods for the synthesis of diverse spiropyran compounds.